Mix together the Butcher BBQ Prime Dust with the vegetable stock, according to the instructions on the packaging (3/4 cup dust to 2 cups stock). Fill a marinade injector with the injection liquid. Working in a grid pattern, inject the rib roast. Depending on how large the roast is, it should take about 1-2 cups of the injection.
Wipe the excess injection from the surface with a paper towel. Season all surfaces of the roast with Cattleman’s Grill Tuscan Steak Seasoning. Let the rub set up for 5-10 minutes.
Smoke the prime rib roast on the second shelf until the internal temperature reaches 110ºF, about 3 hours. Remove the roast. Place in a large pan and cover loosely with foil. Remove the second shelf. Turn the grill up to 425ºF.
When the grill comes up to temperature, place the roast on the GrillGrates, directly over the fire box. Grill on both sides to achieve nice grill marks. Remove the roast when the internal temperature reaches 125ºF. Place in a large pan. Cover loosely with foil and rest 30 minutes before slicing.